Project Summary Life-sustaining therapies, such as central venous catheters and endotracheal tubes, disrupt the body?s natural protective barriers (e.g. skin, mucosal membranes) and provide a natural conduit for infection. Device-associated Candida albicans fungal infections in particular represent a devastating medical complication associated with high mortality and high morbidity. Fungal and human cells share very similar cellular structure and machinery, making it difficult to find drugs that aggressively target the fungal cell without significant toxicity to humans. Additionally, as the number of patients treated for fungal infections has increased, so too has the emergence of drug resistant Candida strains. It is crucial that unique aspects of this fungal pathogen?s biology be identified and exploited to develop new therapies. One unique aspect of Candida pathogenesis is the way it establishes and disseminates infection. Device associated fungal biofilms develop when yeast-form cells adhere to substrate, initiate biofilm formation, and mature. Dispersion of yeast-form cells from the biofilm seed new sites of infection. Candida biofilms exhibit gene regulatory programs that vary in space and time. Currently there is a limited experimental toolbox for Candida to explore how this dynamic, spatially heterogenous gene regulation controls the biofilm lifecycle. In this proposal we will develop optogenetic and microfluidic tools that allow us to better understand how temporal and spatial expression of different putative regulators control biofilm formation and dissemination. Aim 1: Develop flexible optogenetic control of gene expression in Candida albicans We will develop optogenetic tools that allow us to flexibly regulate gene expression in Candida albicans. This system will allow us to repress or overexpress specific genes in Candida albicans biofilms in space and time. Aim 2: Develop a novel in vitro assay to quantify defects in biofilm formation, dispersion and dissemination We will develop an in vitro microfluidic system that allows us to quantify defects in the biofilm lifecycle in response to precise spatiotemporal genetic perturbations. The outcomes of this work will be 1) creation of optogenetic tools for flexibly targeting Candida genes for repression or overexpression in both space and time and 2) development of a microfluidic device that lets us quantitatively monitor the outcome of modulating specific regulators. A better understanding of the uniquely fungal factors that regulate biofilm formation and dispersion may lead to new therapeutics targeting these factors.